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HIGHER ORDER MOMENTS OF PASSIVE AND REACTING SCALARS AND THEIR GRADIENTS IN TURBULENT WALL-JETS

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The concept of local isotropy [1,2] of passive and active scalar fields is addressed for a turbulent wall-jet. A plane wall-jet is
formed when a jet flow is injected parallel and next to a solid surface. At the inlet of the computational domain, both a fuel component
(active) and a passive scalar are injected through the jet stream, within the height h [3]. The mean profiles of the two scalars are shown
in Fig. 1. The remainder of the inlet consists of a coflow with a velocity of the order of 10% of the jet flow and contains 50% of the
oxidizer. The reaction forms in such a way that a considerable amount of fuel is consumed throughout the domain. The main objective
of this study is to use the DNS-database to address the statistical characteristics of both active and passive scalars. In particular, we
discuss the properties of skewness and flatness at large and small scales. The scalar statistics are interesting both for applied problems,
when the large scale properties such as the scalar variance and the scalar flux are examined, and for fundamental ones, concerning the
universal properties of the advected fields.

Author(s):

Zeinab Pouransari    
Mekanik, KTH
Sweden

Luca Biferale    
Tor Vergata, Italy
Italy

Arne Johansson    
Mekanik, KTH
Sweden